Oscillation generator



March 14, 1933. 1.. o. ROOSENSTEIN 1,301,043

OSCILLATION GENERATOR Filed Sept. 4, 1929 /7bediwmbr a l 5 4 1 1 -z 70Ufff/17477064.

IMPI.

7+ mao-mmm HANS oT-ro Roossnsrsm zzaaaaxc. BY' 7 MW ATTORNEY PatentedMar. 14, 1933 Unirse STATES Partnr tries HANS OTT() ROOSENSTEIN, 0FBERLIN, GERMANY, A.SSIGNOR TO TELEFUNKEN GESELL- SCHAFT FUR DRAHTLOSETELEGRAPHIE M. B. H., OF BERLEN, GERMANY, A CORPO- RATION' OF GERMANYOSGILLAT'ION Application led September 4, 1929, Serial No.

For the production of short waves, as is well known from the prior art,crystal-controlled thermionic-tube generators are emf ployed, and theseoffer the practical advantage that they insure an almost absolutelyconstant wave-length. Now in practical work, the p-roblem to vary thecarrier frequency of a transmitter within certain nar row limits, arisesquite frequently; and, a crystal-controlled transmitter does not lenditself readily to such variation.

rShe present invention is concerned with a transmitter arrangement whichfurnishes a useful frequency, which latter, while being extremelystable, is also adapted to be varied quite readily. According to thisinvention, the transmitter outfit consists of the combination of amechanically controlled and preferably crystal controlled thermionicgenerator and a generator which is not subject to crystal control, thatis, most suitably a self?A excited thermionic transmitter or in otherwords, an electrically controlled generator. The auxiliary generatorwhich produces a substantially lower frequency than thecrystal-controlled thermionic transmittenis employed for the modulationof the wave of the crystal controlled transmitter; and, from among theensuing oscillations, one side band is separated by a filter circuit orequivalent means, and used in the usefulA or load circuit. By changingthe frequency of the auxiliary generator, this working or usefulfrequency can be easily varied within definite limits. For instance, ifthe frequency of the crystal controlled transmitter is g and themodulating frequency of the auxiliary generator 7L, there result thesetwo frequencies:

g-lz, and gh one of which is utilized.

In the accompanying drawing, Fig. 1 diagrammatically illustrates theinvention; Fig. 2 is wiring diagram therefor; and, Fig. 3 is a graphexplanatory thereof.

A fundam-ental circuit scheme is shown in Fig. 1 wherein a modulator 3is influenced by two wave generators, the crystal controlled generator 1and the vacuum tube regeneratively connected generator 2 and where thedesired wave is separated by means of a filter circuit 4;.

GENERATOR 390,369, and in- Germany September 10, 1928.V

It is obvious that the working or useful frequency is extremely stableinasmuch as in the presence of fluctuations of the frequency of theauxiliary generator (the wave length of the crystal controlledtransmitter being admissibly considered absolutelyconstant) thepercentage variations of the useful frequency are essentially lower thanlwhen-the useful frequency were generated without `a stable V crystalgenerator. For instance, if the stable frequency 7:20000 kilocycles, andthe modu` lation frequency variable inside thev range 500-2000kilocycles, then the usefulY or working frequency is capable ofvariationinside a range between 18000-19500 and 20500- 22000 kilocycles, asexplained graphically in Fig. 3 where the abscissae stand for thefrequency e and the ordinates for the amplitudes.

@ne specific embodiment of the basic idea of theinvention is shown inFig. 2 by way of example where thetube arrangement or assembly 1Vdenotes the crystal controlled transmitter, the tube 2 the auxiliarygenerator, tube 3 the modulator tube, and 11 is the lter circuit. rlhearrangement according tothe invention may be employed in transmitterapparatus and in receiving apparatus since, as is well known, in manyreceiver apparatus the production of an auxiliary wave, for instance,for heterodyning is necessary and silpce also this heterodyn-e wave mustbe varia le. v

The invention Vis also useful for fading elimination. By wobbling thefrequency of generator2, the carrier output is wobbled andmay be used togood advantage for fading elimination.

Then again, by properly choosing the frequency of generator 2, each ofthe sidebands produced may be used to separately transmit the same orpreferably different signals without interference. side bands for use ascarriers may be accom-V plished by the use of filters.

I claim:

1. Apparatus for the generation of substantially constant frequencyoscillations comprising a mechanically controlled oscillator having ahigh degree of frequency sta- Separation of the bility, an independentnon-mechanically controlled oscillator arranged to generate frequenciesWhich are relatively loW compared to the frequencies generated by saidmechanically controlled oscillator, means for adjusting the frequency ofsaid independent non-mechanically controlled oscillator, and a modulatorhaving input and output circuits for inter-modulating Waves from saidoscillators, said input circuit being coupled to both said oscillators,and a selector circuit coupled't'o the output of said modulator forchoosing a desired Wave from the output 'of said modulator. Y

2. In a system comprising a high frequency piezo-crystal oscillator anda relatively loW adjustable frequency oscillator, the method ofproducing a Wave Whose frequency is variable over a range which is smallcompared to the frequency of said crystal and yet having substantiallythe same degree of frequency stability as the frequency 0f the Waveproduced by said Crystal oscillator, Which consists in intermodulatingWaves from said high frequency crystal controlled oscillator With Wavesfrom said relatively` loW adjustable frequency oscillator, therebyproducing Waves of side band frequencies, and selecting a Wave 'of adesired side band.

3. In a system comprising a. substantially constant vacuum tubeoscillator Whose frequency is controlled by a mechanical resonantdevice, andan independent adjustable frequency oscillator Whosefrequency is 10W `relative to the frequency generated by said vacuumtube oscillator, the method of obtaining ka Wave Whose frequency isvariable over a range Which is small compared to the frequency of saidvacuum tube oscillator and yet having substantially the same degree offrequency stability as the frequency of the wave produced by said vacuumtube oscillator, Which comprises intermodulating Waves from said highfrequency vacuum tube oscillator with Waves from said relatively lowadjustable independent oscillator, thereby roducin Waves of side bandfre uenc and selecting a Wave from a desired side band. HANS OITOROOSENSTEIN.

